Permanently Open Exhaust Valves (How-To)

[PolishPete]

Disclaimer: Do this at your own will, I take no responsiblity for you messing with your car or what happens to the car at any point.

Purpose: The purpose of this mod is to make the valves in the exhaust stay open all the time. Normally the valves are closed, however, when you hit the sport button and drive in sport mode, they open. Rather...they open from below 1,500 rpm, close, then re-open above 3,500 rpm. Since most driving is done within the range of 1,500 - 3,500 rpm, you don't drive with the valves open that much.

Purpose Cont: I wanted to have the valves stay open all the time in order to get a better exhaust note from my stock exhaust.

Details: The valves open when the car is off, and are operated by vacuum lines that connect under the car, in the rear, near the exhaust exits. With the car off and the valves open, if you remove the vacuum lines, then plug them so you don't lose any vacuum pressure, the valves will stay open and not close when the car turns on. Attached are pictures of the valves open, and of the valves closed.

Valve Open:


Valve Closed:


Step One: Locate the vacuum line and pull it off. They are located near the rear of the car, right where the exhaust comes out. You'll see a cylinder type thing with a black hose coming off of it.



Step Two: Use a short screw and screw it into the end of the black hose. Tuck the black hose into the rear valance so they aren't flopping around.


Step Three: Enjoy your new exhaust tone. That's it. You're done.

[NY07RS4]

Such a simple little mod but there are probably folks who didn't know how to complete it. Thanks for sharing, I'm sure some who were afraid to post & ask how to accomplish this are happy you posted this info.

[Mr Hyde]

I actually just did this same mod recently, but I used plastic clamps that just crimp the tubing, and left the lines hookd up to the mufflers. That way I can't get a vacuum leak, and in 5 seconds, I can pop the clamps open without any tools, and quiet things back down if I choose.

I performed this mod for 2 reasons; First was because even with the S button pressed, the flaps still close in certain ranges of the RPM band to comply with euro sound regulations. The second reason is because in many situations, like city driving, I don't like the jerky throttle response the S button gives you.

Nice job with the pics, but the only things I dont like are that you used a screw to plug the lines, and that it looks like you reused the OEM clamps. Threads on a screws can let air leak by, creating a vacuum leak, and a loss of power. Something solid with a smooth finish will create a better seal. I think a few guys even used Golf Tee's to plug those lines.

Those clamps are really a one time use kind of thing, and wont tighten enough if reused. I picked up some hose clamps at Home Depot for less than a dollar a piece that get the job done, and are reuseable.

[JuniorAra]

... I picked up some hose clamps at Home Depot for less than a dollar a piece that get the job done, and are reuseable.

Could you post a pick, I want to do this mod this weekend but I want to get the right clamp. I agree that the screws aren't the best option, and neither is a golf tee since the wood could crack creating a possibility for a leak. TIA

[WinterRunner]

I used screws and have had no leaks for almost 2 years. I also used electrical tape to cover both the screws (for a better securement) and to close up the actuator nipples to keep then clean from debris... I also suggest zip-tieing the loose hoses behind the back valence, but that doesn't really matter...

[Mr Hyde]

I work in a hospital, and the crimps came off some unused surgical drains which were going to be discarded.You probably dont have that option available to you, but home depot is a good start. The red piece you see was another part of the drain which was just a piece of plastic with a hole in one end, and a slot on the other. Sliding the tube towards towards the slotted end crimps the tube also. Since I had them, I just used them both.

If better options are readily available, why not use them. Honestly I think a smooth nail would create a better seal. Ideally I'd use a piece of plastic, or something that wont corrode to plug the lines.

[JuniorAra]

If there is a vacuum leak after doing this mod, would it trigger a CEL? I recently did this and had the CEL come on a day after. Im out of town with the car and just want to make sure its nothing more serious.

[dparm]

Doubtful because it would be a very very small one.

[Krys-RS4]

I have this mod done few months ago with the screw as plug-no leaks,no CEL. Same performance,much better sound! I also taped the end of the hose with the isolation tape and the actuator nipples to keep them clean-that was winterrunners idea which I saw months ago on this forum.

[RAudi Driver]

If there is a vacuum leak after doing this mod, would it trigger a CEL? I recently did this and had the CEL come on a day after. Im out of town with the car and just want to make sure its nothing more serious.

You can have the line completely unplugged and it won't throw a light. You will lose a nice amount of power though.

[BenSti]

You can have the line completely unplugged and it won't throw a light. You will lose a nice amount of power though.

You also lose the 5500RPM kick.

[RAudi Driver]

That's exactly the power I was speaking of. Mine came disconnected right before I started a trip from So Cal to Napa, to Monterey and back to So Cal. When I got home, I posted that I didn't feel the kick and someone mentioned that the hose may have come loose. It did! 1000 miles with no kick, sucks!

[B7audirs4-Harry]

Hi Guys,
I know this post is old, however my B7 RS4 has never really had a god exhaust note, even with the S button pressed.

Upon checking, I've found the drivers side flap is closed all the time!

I used oil and elbow grease to free it. It moved to the open position, but closed again on driving and stayed closed.

So my plan tonight is to remove the hose and place some golf tees into them, gently force open the seized flap and see how it goes.

Lets hope the sound is better!

[B7audirs4-Harry]

All done. Nice and easy, almost as if Audi knew that someone would have thought about doing it.

The main function of the flap is to reduce noise pollution. So how. Come other cars with similar or bigger engines don't have the valve system ?

[c615586]

I found these clamps on the Home Depot website. Would these work?

[rs4StigA]

Old thread but I just saw the valve on passenger side never open ? Could this cause power loss if it's a vacum leak?

The seller told med the valves are open all the time for a better sound. The car run very bad now.. .. but I dont know if this has been like this all the time or just happened.

[Mr Hyde]

You would have to check the lines themselves to see if there are any leaks. Corrosion, salt, sand, etc can bind the flaps, so some people have needed to manually loosen the flaps by pushing on them, and then working in some lubricant to make sure they rotate freely.

If the prior owner capped the lines to open the valves, they should have opened, and stayed open, so it doesn't make sense that they are now closed.

[xspace]

Can this be done on S5 B8.5?

[Matt Devo]

Can this be done on S5 B8.5?

probably best to ask in the proper forum for the B8/8.5, but I believe the newer cars use an electrically controlled actuator rather than a vacuum driven one

[Onkar02]

I was doing some research across Audizine and found an alternative way to keep the valves open at all times thanks to member "frankvan"

Link: https://www.audizine.com/forum/showt...-Flap-Solenoid

In his words "The system is behind the left rear wheel in the trunk. If you have a storage bin there simply open the storage bin and remove the floor tray and you'll see a light blue triple sphere vacuum reservoir. The solenoid is mounted to a bracket on top of the reservoir. I just simply unplugged the electrical connector to the solenoid. All my vacuum hoses are still attached - no plugging of vacuum lines with screws or golf tees."

I have had it unplugged for over a week now with no issues, but if anyone has more clarity on this method.. would love to hear.

[GrandMarkie]

I was doing some research across Audizine and found an alternative way to keep the valves open at all times thanks to member "frankvan"

Link: https://www.audizine.com/forum/showt...-Flap-Solenoid

In his words "The system is behind the left rear wheel in the trunk. If you have a storage bin there simply open the storage bin and remove the floor tray and you'll see a light blue triple sphere vacuum reservoir. The solenoid is mounted to a bracket on top of the reservoir. I just simply unplugged the electrical connector to the solenoid. All my vacuum hoses are still attached - no plugging of vacuum lines with screws or golf tees."

I have had it unplugged for over a week now with no issues, but if anyone has more clarity on this method.. would love to hear.

I originally did the golf tee method then discovered this method you mentioned....so much easier and can go back to using valves within 10 seconds. Been doing this for a few years now with no issues.

[Kenny147]

Anyone care to explain how the heck you remove the base of the storage tray? Tried to but gave up because I thought I was going to break something.

TIA

[WhatsATurbo]

Pull up and towards you on the edge closest to the trunk...did mine after work today after reading this. No tools needed other than something to unclip the connector (used my key, very carefully).

[S4Bennett]

My apologies for thinking this was a joke related to bending all of the exhaust valves in the cylinder heads lol.

[Onkar02]

Pull up and towards you on the edge closest to the trunk...did mine after work today after reading this. No tools needed other than something to unclip the connector (used my key, very carefully).

Yea it can be a little tricky, but just yank on the end closest to the trunk.. should pop right out... nothing really to break.

[Kenny147]

Yea it can be a little tricky, but just yank on the end closest to the trunk.. should pop right out... nothing really to break.

Pull up and towards you on the edge closest to the trunk...did mine after work today after reading this. No tools needed other than something to unclip the connector (used my key, very carefully).

Thanks guys, I’ll give it a go.